ph03n1x
This chart leads me to believe that 2.6 is not available for SPARC.
I know weeve has it running.
This is not a production box just my desktop machine. myDual X86 system runs great on the 2.6 kernel.

So if anybody else can say they have migrated from 2.4 to 2.6 what other steps are used?

If you have a look at the chart again you can see that 2.6.13 should be available with ~sparc for testing. That should be stable enough to use it on your desktop system. But then on the other hand I don't have any sparc experience myself.

Kernel-2.6.x is generally available for testing on sparc, but it is not stable on sparc because it is known to fail on some systems. In particular, it is not yet recommended for U1/U2 systems because of random hard lockups. For my own testing and use, I generally use vanilla sources (even though they have no sparc keyword at all right now). Kernel-2.6.14 seems to be stable generally, but not on U1/U2. With a U1-Creator system, you might or not have good results.

Sorry I can't be more definite. We don't know what the problem is yet.